I wanna say shiny Shroomish but this shiny orange Minior popped up out of nowhere. Oh well, why not both?
Ah! Those letters refer to the region. For example, Eevee (K) means Kanto, so it'll evolve into Flareon, Jolteon, or Vaporeon, but only those three. KS is Kalos (Sylveon), and so on. My last mon caught was a Shiny Grubbin.